Recently, van der Waals heterostructures (vdWHs) based on transition‐metal dichalcogenides (TMDs) have attracted significant attention owing to their superior capabilities and multiple functionalities. Herein, a novel vdWH field‐effect transistor (FET) composed of molybdenum ditelluride (MoTe₂) and palladium diselenide (PdSe₂) is studied for highly sensitive photodetection performance in the broad visible and near‐infrared (VNIR) region. A high rectification ratio of 6.3 × 10⁵ is obtained, stemming from the sharp interface and low Schottky barriers of the MoTe₂/PdSe₂ vdWHs. It is also successfully demonstrated that the vdWH FET exhibits highly sensitive photo‐detecting abilities, such as noticeably high photoresponsivity (1.24 × 10⁵ A W⁻¹), specific detectivity (2.42 × 10¹⁴ Jones), and good external quantum efficiency (3.5 × 10⁶), not only due to the intra‐TMD band‐to‐band transition but also due to the inter‐TMD charge transfer (CT) transition. Further, rapid rise (16.1 µs) and decay (31.1 µs) times are obtained under incident light with a wavelength of 2000 nm due to the CT transition, representing an outcome one order of magnitude faster than values currently in the literature. Such TMD‐based vdWH FETs would improve the photo‐gating characteristics and provide a platform for the realization of a highly sensitive photodetector in the broad VNIR region.

Since two‐dimensionalal (2D) materials have distinct chemical and physical properties, they are widely used in various sectors of modern technologies. In the domain of diagnostic biodevices, particularly for point‐of‐care (PoC) biomedical diagnostics, 2D‐based field‐effect transistor biosensors (bio‐FETs) demonstrate substantial potential. Here, in this review article, the operational mechanisms and detection capabilities of biosensing devices utilizing graphene, transition metal dichalcogenides (TMDCs), black phosphorus, and other 2D materials are addressed in detail. The incorporation of these materials into FET‐based biosensors offers significant advantages, including low detection limits (LOD), real‐time monitoring, label‐free diagnosis, and exceptional selectivity. The review also highlights the diverse applications of these biosensors, ranging from conventional to wearable devices, underscoring the versatility of 2D material‐based FET devices. Additionally, the review provides a comprehensive assessment of the limitations and challenges faced by these devices, along with insights into future prospects and advancements. Notably, a detailed comparison of FET‐based biosensors is tabulated along with various other biosensing platforms and their working mechanisms. Ultimately, this review aims to stimulate further research and innovation in this field while educating the scientific community about the latest advancements in 2D materials‐based biosensors.